Disposable syringe

ABSTRACT

A dispensing syringe is provided having a liquid-fill compartment between an inner piston and an outer piston. In storage the inner piston is partly pierced by the inner end of a two-way syringe cannula and serves to divide the syringe barrel in two parts: one, a head space and the other the mentioned compartment separate from the syringe cannula. To avoid changes of pressure in the head space the hub has a bypass structure for venting. The syringe is operable by reciprocation to bring the liquid-fill in direct communication with the syringe cannula for mixing purposes, aspiration and injection by conventional techniques. The syringe components are standardized for use with conventional dispensing components such as vials, needle covers, etc. The head space has a closure hub on the free end thereof, the hub having a gasket in the form of a disc having a radial channel therein so that the head space may be vented to atmosphere in storage or when the inner piston is moved toward the hub for bringing the liquid-fill into communication with the cannula as noted.

United States Patent [72] Inventors Ralph E. Mottin Grosse Pointe Park; Carl C. Garland, Detroit with of. Mich. 1211 Appl. No. 837.408 [22] Filed June 30, 1969 [45] Patented Sept. 7, 1971 173] Assignce Parke, Davis & Company Detroit. Mich.

[54] DISPOSABLE SYRINGE 4 Claims, 6 Drawing Figs.

[52] U.S. Cl 128/218 R, 128/221, 215/56 (51] InLCl ..A6lm 05/22,

A61m 05/32 [50] Field of Search 128/218, 221, 218 NV; 215/56 [56] References Cited UNITED STATES PATENTS 1,596,004 8/1926 De Bengoa 1. 128/221 2,460,039 1/1949 Scherer et al.. 128/218 (NV) 2,607,341 8/1952 Brown 128/218 (NV) 2,735,428 2/1956 Huber 128/218 (NV) 2,826,196 3/1958 Pieke 128/221 2.893.390 7/1959 LockharL. 128/218 (NV) 3.115.137 12/1963 Sarnoff 128/218(NV) FOREIGN PATENTS 1.252.251 12/1960 France 128/221 Primary Examiner-Joseph S. Reich Attorneys-Robert R. Adams, David E. Ehrlinger, George M.

Richards and Edward .1. Gall ABSTRACT: A dispensing syringe is provided having a liquidfill compartment between an inner piston and an outer piston. ln storage the inner piston is partly pierced by the inner end of a two-way syringe cannula and serves to divide the syringe barrel in two parts: one, a head space and the other the mentioned compartment separate from the syringe cannula. To avoid changes of pressure in the head space the hub has a bypass structure for venting. The syringe is operable by reciprocation to bring the liquid-fill in direct communication with the syringe cannula for mixing purposes, aspiration and injection by conventional techniques. The syringe components are standardized for use with conventional dispensing components such as vials, needle covers, etc. The head space has a closure hub on the free end thereof, the hub having a gasket in the form of a disc having a radial channel therein so that the head space may be vented to atmosphere in storage or when the inner piston is moved toward the hub for bringing the liquid-fill into communication with the cannula as noted.

PATENIEDSEP 1m:

RALPH EI W'WW BY CARL c. GARLAND WEE/kw ATTY. a

DISIPDSABLIE SYIRINGIE SUMMARY AND DETAILED DESCRIPTION The invention relates to disposable dispensing syringes of an improved type having a liquid-fill compartment which is separate from contact with the syringe cannula. More particularly, the invention relates to syringe apparatus of an improved type for general dispensing purposes operable by reciprocation for use with standard syringe vial components.

Prior to the present invention various devices and syringe means have been proposed for dispensing fluids of the type which are pharmaceutically sensitive or incompatible with metallic surfaces of the surgical cannula. Some of these prior art devices have been unduly complicated or expensive or have not been interchangeable for use with systems involving standard syringe vial components.

It is therefore an object of the present invention to provide syringes of an improved type which are economical and which maintain the syringe contents in proper form until ready for use.

It is also an object of the invention to provide simple syringe means for supplying a sensitive syringeable liquid for injection purposes and the like using standard techniques.

It is a further object to provide syringe apparatus of the kind described which can be readily used and can be discarded following a single use.

It is a still further object of the invention to provide syringe means which can be sterilized prior to use as desired without impairing the integrity of the liquid-fill, without liquid loss, etc.

These and further objects, advantages and purposes will be seen in relation to the following description and the accompanying drawing in which:

FIG. I is a plan view of a preferred embodiment of a syringe according to the invention;

FIG. 2 is a similar, fragmentary representation of a syringe shown in operating position;

FIG. 3 is an assembly view of asyringe barrel segment and the associated cannula, hub, and gasket components, according to the invention;

FIGS. 4 and 5 are detailed views in perspective of gasket means of different types; and

FIG. 6 is a fragmentary perspective view partly in section of a preferred embodiment of a syringe piston having a recess in the inner surface and a cannula point exposed therein.

Referring to FIG. l, a preferred form of the syringe according to the invention includes a syringe barrel I0 with an open end bounded by a peripheral flange Ill. The barrel includes a main piston or outer piston 12 having sealing rings 12a. The piston is attached to head 14 by way of stem 13 for axial reciprocation in the barrel. At its opposite end the barrel has a shoulder 15 and neck to terminating in an opening bounded by flange llfia. Mounted on the flange is hub l7 which supports a two-way cannula 119 having an outer end Ztla and an inner end b.

Within the barrel is a fill zone 21 (inert with respect to the pharmaceutical fill intended and preferably nonmetallic) for liquid retained by the main piston I2 and an inner or floating" piston 22 having sealing rings 22a. The pistons are of a construction which is suitable for syringes being conveniently made of rubber or similar material and being adapted to operate in cooperation with the inner walls of the barrel to provide a fluidtight contact both during axial movement of the pistons within the barrel and for long periods during storage prior to actual dispensing of the syringe contents. The pistons and barrel preferably are pretreated by lubrication with silicone grease or other lubricant. As seen in FIG. I, prior to dispensing, the cannula end 20b extends axially within the central axis of floating piston 22. The piston as represented serves to seal over the open end Zhb of the cannula and prevents communication between the cannula bore and the fill zone. Also, the piston prevents contact of the cannula used should be low in cost in order for it to be practical to dispose of the syringe after a single use.

Referring to FIG. 3, the hub and cannula are mounted on the flanged neck ll6 of the barrel by crimping, swaging, spinning or other suitable forming method. To assure a snug fit on the barrel in one preferred form of the invention, a gasket 30 (preferably resilient rubber) is placed in registry with the flange and the hub face I180. The inner walls 18b of the hub are then crimped or formed over the flange 16a to provide the snug fit required. The gasket 30 includes the bypass channels 32 and 32' and cannula recesses 33 and 33', as seen seen in FIGS. 4 and 5. The axial cannula recess facilitates locating the gasket in relation to the hub face 18a and the flange 16a. The bypass channel 32 provides for escape of air from the head space 23 by way of the narrow space between the hub wall 18b and the flange 16a. In this way air pressure in the head space 23 in the barrel between the floating piston 22 and the gasket 30 is permitted to be relieved, particularly at critical periods when the packaged syringe is steam sterilized or stored at high temperature or when the main piston I2 is abruptly reciprocated or depressed inwardly for ejection of the syringe contents from the barrel. The invention also contemplates bypass means wherein the gasket is omitted and the hub face 118a and/or inner walls 18b are gap-fitted, channeled or perforated to provide communication to the atmosphere. An example of the same may be found in the Williams Pat., No. 3,437,224.

Operation Dispensing, Aspiration, Injection Dispensing To operate the syringe the main piston I2 is manipulated by squeezing flange Ill and head 14 together in conventional fashion to cause the piston to move axially towards the floating piston. Since the liquid contained in the fill zone 21 is substantially incompressible, the pressure exerted is transmitted immediately to the floating piston which undergoes a cor responding axial movement towards the cannula end of the syringe. In so doing the inner piston moves to the position shown in FIG. 2. The relative dimensions of the piston, cannula shank and shoulder advantageously are such that the piston stops at this point with the result that the inner end 20b of the cannula becomes exposed but only partly exposed. In this position the liquid contained in the syringe has immediate access to the interior of the cannula and, being under pressure, is forced and ejected from the cannula as desired. In addition to the hydraulic pressure effect described the bottom of the main piston during the final portion of its inward excursion also exerts a contacting force on the top of the inner piston (by predetermined positioning of the piston, cannula and barrel) to cause the piston to shift inward slightly and to remain stationary in the terminal position shown in FIG. 2.

While the inner piston is moving to the latter position it continually exerts a positive pressure on head space 23. As indicated previously, however, the pressure in the head space is automatically relieved along the path indicated by the arrow in FIGS. 4 and 5, through the bypass channels 32 and 32' past flange Ida and the adjoining portion of hub wall 18b to the surrounding exterior atmosphere. Thus, the inner piston 22 freely and controllably moves, without opposing restraint, to the desired position for dispensing in. conventional manner. Advancement of the main piston as described accomplishes three important objectives: it serves to dispense the fluid fill in controlled fashion, it binds the floating piston, and it locates the piston precisely so that the piston interface 22b can cooperate with the cannula end b during any subsequent operation of injection following aspiration, particularly where air bubbles are present in the fill zone.

As the liquid is dispensed (for example, for mixing purposes), the main piston 12 approaches piston 22 and because of the particular arrangement of the cannula inner end 20b in relation to the piston-fill zone interface 22b the liquid is completely dispensed. The invention also contemplates a preferred alternative in which the parts are so constructed that a residual portion of the liquid-fill is retained within the fill zone 2l but the barrel is calibrated visually in volume units (for instance, in the way shown in US. Pat. No. 3,192,925) so that the operator can control the volume of fill actually dispensed.

Aspiration The syringe of the invention can be used for purposes of hypodermic injection and the like or it can be used for purposes of mixing the liquid-fill with a separate pharmaceutical component, diluent or other component as in a mixing vial. When mixing is complete, the resulting mixture or solution can then be aspirated back into the fill zone 21 by retraction of the main piston 12 to its position shown in FIG. 1. In this case, however, according to the invention, the floating piston 22 advantageously remains stationary in the terminal position. In other words, by means of the bypass channel in cooperation with the hub construction described there is no tendency (as there would be without a bypass) for the inner piston to move back to its original position. In other words, once the inner piston has been actuated from its FIG. 1 position to the terminal position of FIG. 2 the inner piston remains in the latter position according to the invention for all subsequent purposes. Thus, the mixture which is aspirated into the fill zone 21 as described, can thereafter be injected.

Injection For injection, the syringe with aspirated fluid is held with the cannula upright in the conventional way with the meniscus of the liquid-fill lying just below the interface 22b. The liquid level is then carefully raised by appropriate pressure on the main piston to cause all entrapped air to leave the fill zone and cannula bore above the rising level of the liquid-fill. The liquid-fill level is then brought up to open end 20a and the liquid injected in the usual way. In this regard, the invention also includes the embodiment illustrated in FIG. 6. In this embodiment, the selective expulsion of air bubbles preceding the liquid-fill is facilitated by cooperation among the interface 22b, the exit walls 22c, exit face 22d, and cannula 20b. Here, as the fill meniscus is raised to the interface 22b the particular configuration favors the direction of entrapped air or bubbles to the central exit zone defined by the exit walls and face. Then, when the liquid level is raised in due course the same advances the air with precision to the open end of the cannula and beyond through the cannula bore with the result that the following liquid delivered to the outer cannula end 20a is completely free of air bubbles.

Aside from the advantages referred to above, the component parts of the present syringe are, with the exception of the gasket 30, conventional components so that the same are economical and do not require special manufacture. The cannula and the associated hub can be made of any of various materials. The cannula is preferably made of stainless steel. The hub is aluminum or plated brass. No other metallic parts are required for the syringe. If desired, the outer end 20a of the cannula can be packaged with a suitable needle guard or other protective covering. The materials of the syringe are selected for sterilization properties. Thus, once the syringe is filled with a suitable liquid-fill the syringe can be sterilized and packaged for distribution. Sterilization in this manner does not affect the relationship of the component parts since any pressures generated during the sterilization process are completely relieved without impairing the liquid seals, particularly the seal involved at the floating piston 22 in the position covering the inner end 20b of the cannula, especially since the pressure enerated in head space 23 is automatically relieved by way of t e bypass channel 32 even with the outer end 20a of the cannula sealed during sterilization with a suitable cannula cover, vial or other protective cover.

While the present invention in syringes has been described in the foregoing description in considerable detail, it will be realized by those skilled in the art that wide variation can be made in such detail, all within the spirit of the invention, as claimed in the following claims.

We claim:

1. A syringe comprising in combination a cylindrical syringe barrel, an outer piston and a pierceable inner piston, the pistons being adapted to be spaced apart in the barrel to define with the barrel a liquid-fill zone therein and being further adapted to be moved axially within the barrel in fluidtight contact therewith,

a cannula having an inner end extending axially within the barrel and an outer end for ejecting fluid from the fill zone, the inner piston being positioned in sealing relation with respect to the inner end of the cannula and adapted to be axially moved from the sealing position to a dispensing position exposing the inner end of the cannula to the fill zone,

the cannula having an opening in the inner end thereof, the cannula, barrel and inner piston defining a variable head space within the barrel,

and means for mounting the cannula on the barrel, the mounting means being adapted for venting the head space independent of the cannula opening, the mounting means including a hub secured to the syringe by means comprising a bypass providing the venting to the atmosphere from the head space said mounting means including gasket means within said hub, the gasket means providing channel means for providing said bypass means.

2. A syringe according to claim 1 wherein the inner piston is spaced from the outer piston, the zone between the pistons including a liquid-fill.

3. A syringe according to claim I wherein the inner piston is axially movable from the sealing position to a dispensing position exposing the inner end of the cannula.

4. A syringe according to claim 2 wherein the inner piston is movable by axial pressure on the liquid-fill in the fill zone by the outer piston. 

1. A syringe comprising in combination a cylindrical syringe barrel, an outer piston and a pierceable inner piston, the pistons being adapted to be spaced apart in the barrel to define with the barrel a liquid-fill zone therein and being further adapted to be moved axially within the barrel in fluidtight contact therewith, a cannula having an inner end extending axially within the barrel and an outer end for ejecting fluid from the fill zone, the inner piston being positioned in sealing relation with respect to the inner end of the cannula and adapted to be axially moved from the sealing position to a dispensing position exposing the inner end of the cannula to the fill zone, the cannula having an opening in the inner end thereof, the cannula, barrel and inner piston defining a variable head space within the barrel, and means for mounting the cannula on the barrel, the mounting means being adapted for venting the head space independent of the cannula opening, the mounting means including a hub secured to the syringe by meaNs comprising a bypass providing the venting to the atmosphere from the head space said mounting means including gasket means within said hub, the gasket means providing channel means for providing said bypass means.
 2. A syringe according to claim 1 wherein the inner piston is spaced from the outer piston, the zone between the pistons including a liquid-fill.
 3. A syringe according to claim 1 wherein the inner piston is axially movable from the sealing position to a dispensing position exposing the inner end of the cannula.
 4. A syringe according to claim 2 wherein the inner piston is movable by axial pressure on the liquid-fill in the fill zone by the outer piston. 